An electrical precision test connector assembly comprising an electrical conductor with conductive end portions and a hollow shell encircling the electrical conductor is utilized to connect a testing device with a subject ferrite component which is to be tested for electrical continuity, short circuiting or to determine reflection coefficient and the like. More particularly, the precision test connector is utilized in the testing of a ferrite component such as a circulator or isolator operating at microwave frequencies and having thin and narrow tab leads. Exacting standards of performance are set for these components.
Circulators and isolators provide nonreciprocal transmission paths, i.e. microwave energy may travel the transmission path in one direction with little loss but will be greatly absorbed when applied from the opposite direction. The nonreciprocal action provides useful benefits, and circulators are commonly used as duplexers in connection with a transmitter, antenna and receiver, as coupling elements in reflection amplifiers, such as parametic amplifiers and tunnel-diode amplifiers, or in conjunction with bandpass filters. Isolators are used between transmitter and antenna in communications and radar systems to eliminate energy reflected from the load back to the source. Resonance isolators are used as interstage isolators to minimize reflections between circuit elements.
The present invention is applicable to so-called "drop-in" components, particularly circulators and isolators, which are microminiature ferrite devices having input/output tab leads whereby the component with a tab lead is "dropped" onto a printed circuit board and the lead is soldered to form a connection thereto. The tab leads are extensions of the circulator/isolator center conductor itself. The leads may be made of gold-plated beryllium copper. The tab leads are preformed at manufacture to provide optimum contact with the circuit and a tension-free solder joint.
In the testing of circulators and isolators with tab leads, the ferrite component is connected by solder to a single trace micro-strip transmission test fixture and thereto a testing unit such as an automatic vector network analyzer, for the purpose of testing for return and insertion loss to determine reflection coefficient. Connecting testing unit and ferrite component is a time consuming process. Further, the tab lead itself may be damaged by soldering to the test fixture. Indeed, manufacturers recommend that customers test the circulator or isolator components only if there is an unusual need for precise measurement of performance prior to actual use.
Other problems associated with the testing of such components include maintaining a complete, firm and reproducible electrical contact between the tab lead of the component and the testing unit. Results obtained during one testing must be reproducible with further testing, and this depends, to a great degree, on consistent, nonvarying electrical contact between tab lead and testing unit. Further, test data obtained by performing the test must be nonvarying while the test is being conducted over a time interval. Further, the test data must be consistent with test data obtained from repeated tests performed to assure that the ferrite component will retain its ability to operate according to desired standards. Reproducibility over periods of time again is affected by the reliability of the particular electrical precision test connector that connects the ferrite component to the testing unit.
Known test connectors include Vlijimen, et al., U.S. Pat. No. 3,627,929 relating to the distribution frame of a telephone exchange having a break jack assembly for disconnect cross connection and for connection to a test plug unit. The assembly has contact springs with rectilinear portions to provide flat contact surfaces. The flat contact surfaces are urged into contact with a plug member of a test plug unit. Keller, et al., U.S. Pat. No. 4,734,651, describes a device for testing for electrical continuity and short circuits between terminals of a multicontact electrical connector and conductive cores of electrical leads.
The device of the present invention is an electrical precision test connector assembly for interconnecting a testing unit with a subject component which is to be tested for electrical continuity, reflection coefficient or the like.
Forney, Jr. et al., U.S. Pat. No. 4,441,781 relates to a method for terminating coaxial cable and discloses a connector having a front shell, a rear shell, a dielectric insert, a center contact, a coupling and a locking ring. Johnson, U.S. Pat. No. 4,580,862, and Fisher, U.S. Pat. No. 4,697,859, disclose spring biased, float mounted connectors for coaxial cables.
The test connector of the present invention is characterized by an electrical conductor with a flexible, slotted end portion for slideable, clamping engagement with a tab lead of a ferrite component such as a circulator. Further, the shell of the test connector is spring biased so that its circular end is urged into complete annular, electrical contact with the body of the component to be tested.